The milling cutter should be used for machining planes, steps, grooves, forming appearance and blocking workpieces on the milling machine of the cnc machining center. This has a great influence on the quality of the processed parts, so how to choose the appropriate milling cutter? What are the principles?
The milling cutter used in the cnc machining center should be made of all hard alloys, and the white steel material is generally used for milling machines. White steel milling cutters are harder than carbide milling cutters. Carbide milling cutters have good thermal rigidity and wear resistance, but poor impact resistance. If the blade is dropped at will, it will break. The hard alloy is made of powder metallurgy. The hardness can reach about 90HRA, and the thermal property can reach about 900-1000 degrees.
When selecting a milling cutter, consider the number of teeth. For example, a coarse-tooth milling cutter with a diameter of 100 mm requires only 6 teeth, while a dense-tooth milling cutter with a diameter of 100 mm can have 8 teeth. The size of the tooth pitch will determine the number of cutting teeth that participate in the cutting together during milling, which affects the smoothness of the cutting and the requirements for the cutting rate of the machine tool.
Coarse tooth milling cutters are mostly used for roughing because of their larger chip pockets. Assuming that the chip pocket is not large enough, it will cause difficulty in chip curling or increase the conflict between the chip and the tool body and workpiece. Under the same feed speed, the cutting load of each tooth of the coarse tooth milling cutter is larger than that of the dense tooth milling cutter.
CNC processing aluminum shell
The cutting depth is shallow during fine milling, generally 0.25-0.64mm. The cutting load per tooth is small (about 0.05-0.15mm), the required power is not large, you can choose a dense tooth milling cutter, and you can choose a larger feed.
When performing heavy-duty rough milling, excessive cutting force can cause the machine tool with poor rigidity to vibrate. This chatter will cause chipping of the carbide insert, and then shorten the tool life. The use of coarse-toothed cutters can reduce the power requirements of the machine tool.
The price of the milling cutter used in the cnc machining center is relatively expensive. The price of a face milling cutter with a diameter of 100mm may be three or four thousand yuan, so it should be selected steadily. Many people who have operated cnc machining centers have encountered overcutting problems, so how to deal with this situation?
The machining process of workpieces in the cnc machining center is no longer the same as that of traditional machining equipment. It requires continuous operation of the machine tool to end, and the various functional parts of the machine tool are operated in messy and precise actions, and then the processing process is ended with high precision and efficiency. The preparation of the workpiece processing program is the key to the workpiece processing of the machining center. However, if the programming is unreasonable or the parameter settings are improper, it will seriously affect the processing accuracy and processing power of the workpiece, such as overcutting. Over-cutting is a relatively serious problem in workpiece processing. When severe, it can cause the workpiece to be scrapped. The first-line processing personnel have compiled a processing program that must be over-cutting for some reason during NC programming. The system can announce the alarm signal in advance during the work process, so that the over-cutting incident can be avoided. How to judge the cause of overcutting in cnc machining center?
CNC machining aluminum parts
When the internal arc machining is performed in the machining center, if the selected tool radius rD is too large, the over-cutting is likely to occur when the required arc radius R is processed. CNC machining programs are compiled according to the general practice track of the workpiece, without considering the movement track of the tool in the practical machining process. Because of the existence of the tool radius, the tool practical track becomes coarse and does not coincide with the programmed track. In order to obtain a correct summary of the workpiece surface, it is necessary to set the tool radius compensation command between the tool track and the programmed track. Otherwise, over-cutting of the workpiece will be inevitable.
When machining a workpiece composed of straight segments in a cnc machining center, if the tool radius is too large, it will most likely overcut, and then cause the workpiece to be scrapped. The positive and negative of the scalar product of the programming vector and its corresponding correction vector can be judged.